U.S. Pat. No. 5,137,039 discloses a straddle-type tooth brushing device comprising means including a pair of elongated arms having tooth brushing means on the distal end portions thereof forming a head for straddling about a row of teeth to be cleaned, elongated support means including a handle for supporting the head adjacent the row of teeth, and leveraging means acting on the tooth brushing means from within the head to yieldably bias the tooth brushing means into engagement with the inside and outside faces of the teeth when the head was straddled about the row thereof. The support means had a distal end, and the arms had longitudinal axes and were rigidly interconnected with the support means at the distal end thereof so as to form relatively rigid longitudinal extensions of the support means which projected from the distal end of the support means in generally spaced parallel relationship to one another and had an elongated slot in the space therebetween which was coextensive with the arms and opened to the outside of the device between the distal end of the support means and the distal end portions of the arms in a central plane of the slot extending between the longitudinal axes of the arms generally parallel thereto. The distal end portions of the arms, meanwhile, had pairs of generally laterally inwardly and outwardly directed surfaces thereon, the laterally inwardly directed surfaces of which were relatively opposed to one another across the central plane of the slot, extended in planes generally parallel to the longitudinal axes of the arms, and had relatively upper, lower and forward edges formed about the peripheries thereof, which were interconnected with one another by the laterally outwardly directed surfaces of the distal end portions of the arms at the outsides thereof, and were disposed relatively remote from, and adjacent to the gum lines of the respective row of teeth being brushed, and forwardly of the surfaces, respectively, when in an operational mode of the device, the head was straddled about the row of teeth so that the central plane of the slot was aligned with the row of teeth, the arms were generally parallel to the row, and the laterally inwardly directed surfaces of the distal end portions of the arms were generally opposed to the inside and outside faces of the teeth in the row. The tooth brushing means comprised a monolithic cowling of plastic resin material which had an operatively inverted U-shaped body extending crosswise the plane of the slot and was comprised of a pair of relatively endmost sections that were spaced apart from one another and mounted on the distal end portions of the arms to form brush forming members thereon that opposed one another across the central plane of the slot and were yieldably biased by the leveraging means to engage the faces of the teeth when the head of the device was straddled about the row of teeth in the operational mode of the device; and moreover, a mid-section which was interconnected with and between the endmost sections of the cowling and flexibly interposed in the slot between the relatively upper peripheral edges of the distal end portions of the arms to form an articulated linkage between the brush-forming members which was spaced apart from the distal end of the support means by the openings of the slot to the outside of the device and operable to preserve the bias on the brush forming members when the head adjusted to the varying diameters of the teeth crosswise the central plane of the slot in the operational mode of the device. The brush forming members had oppositely disposed fields of bristles thereon, the bristles of which were formed by strands of the plastic resin material that upstood monolithically on the brush forming members and were so individually spaced apart from one another on the brush forming members as to be individually laterally deflectable in relation to one another, yet collectively operable to form brushes for the faces of the teeth.
In one group of embodiments, the arms were resiliently flexible crosswise the central plane of the slot, and the distal ends of the arms had laterally projecting jaws thereon, which defined the relatively laterally inwardly and outwardly directed surfaces of the distal end portions of the arms and the relatively upper, lower, and forward edges about the peripheries thereof. The jaws were so operatively inclined to the central plane of the slot in the direction relatively upwardly of the plane, that the jaws yieldably biased the brush forming members relatively toward one another transverse the central plane of the slot for engagement with the faces of the teeth. In certain embodiments, moreover, the jaws were so closely spaced apart from one another at the relatively laterally inwardly directed surfaces thereof, and the tooth brushing members so yieldably biased relatively toward one another in the relaxed state of the device, that the user had to forcibly wedge the teeth between the brush forming members when inserting the teeth between the jaws in the operational mode of the device.